100 OBJECTIONS TO THE HYPOTHESIS [pt.i,ch.ix 



a very marked alteration of climate. Ordinary ecological barriers, 

 which most often, perhaps, are not very broad, will usually 

 only be able to check it. The check may be long-lasting, but 

 often the succession (pp. 51, 20) which usually occurs in plant 

 societies may give opportunity for passage. Further, by working 

 with groups of ten one allows for chance differences, and by 

 working with groups of allies one obtains groups upon which 

 all the various factors will probably operate in a more or less 

 uniform way, so that their rate of (total) dispersal will be more 

 or less uniform. 



Finally, one Avriter does not like big changes; (32) "if the 

 camel can go through the eye of the needle, the gnat can follow." 

 In other words, presumably, if age can produce such effects, the 

 various later conclusions to which we shall presently proceed 

 will present little difficulty. But if large changes were not 

 sometimes made in our way of looking at things, progress 

 would be remarkably slow. Even if the new point of view is 

 not permanently adopted, it ^^^ll do no harm to spend a little 

 time there. 



In conclusion, it may be noted that many of these objections 

 will perhaps cease to be urged in view of the interesting facts 

 to be brought up in the next few chapters, facts which will 

 quite possibly educe an entirely fresh set of objections. 



